No White Lights
White light ruins the dark adaptation that your eyes develop after about
20 or 30 minutes in the dark. You will need this dark adaptation to see
faint, deep sky objects. When a white light is used after dark anywhere
in the vicinity of the observing field (flashlights, car headlights, even
a match) it takes up to 30 minutes for everyone to regain their night
vision. Once your eyes adapt to the darkness, you will be able to find
your way around and avoid obstructions without needing a flashlight.

How to Make an Astronomy Friendly Light
The best solution is to use a red filter or lens on flashlights, or to
buy a special red LED light. However, it is very simple to adapt a regular
white flashlight to make it friendly to your eyes. All you need to do
is cover it with anything red. Applying several coats of red fingernail
polish to the flashlight lens is an inexpensive way to make a permanent
astronomy light. Temporary astronomy lights can be made by covering a
regular flashlight with a thick layer of non-flammable red paper or plastic
and securing it with a rubber band. Some materials that can be used are
listed below:

Red plastic gift basket wrap

Red brake-light tape

Small patch of red cloth

Printed page of solid red on your inkjet printer

No Flash Photography
The bright strobe of a camera flash can destroy everyone's night vision
for 45 minutes to an hour.

Walk and Drive Carefully
Avoid kicking up dust with your feet or your car. Dust and rocks are not
friendly to telescope optics. Don't kick the dirt and avoid running (a
bad idea in the dark, anyway).

Ask Before Touching
Some astronomers may be adjusting their equipment or the telescope may
not be aimed at any object in particular. So, please ask before touching
or moving a telescope or other equipment. But don't be afraid to ask.
Never touch any glass optical surface.

Be Careful of Food and Drink
Don’t take food or drink around the telescopes. Food and drink can
ruin an optical surface.

Observing At A Star Party
Once the observing is underway, feel free to go from scope to scope and
talk with everyone. They'll be more than happy to let you look through
their scopes, and will also be glad to talk about the telescope, what
they're looking at and anything else that interests you. This kind of
discussion and chitchat is expected at star parties, particularly from
visitors; don't feel that you are imposing on them. Most star party attendees
will "make the rounds" at least once during the night to see
what others are looking at and what kind of equipment they brought; feel
free to join in.

Likewise, don't be afraid to ask questions about what's
in the sky, where different constellations are or anything else. Astronomers,
particularly amateur astronomers, are used to questions like that and
they typically enjoy explaining such things to other people.